At present, use of array components such as QFN, BGA, Flip chip, CSP and the like are more and more widely being used. To ensure the welding quality at invisible welding points of these components during the process of assembling electronic circuit boards, X-ray inspection devices are gradually becoming more and more indispensable inspection tools. This is mainly because the X-ray device is capable of penetrating through packages and directly checking the quality of the welding points.
In the current market, X-ray inspection system applied to BGA and CSP are mainly categorized into two dimensional systems and CT systems. All these devices support offline operation or online operation, and may be used in online inspection and sampling inspection. Whether to select an offline device or an online device depends on the specific application scenario.
All the X-ray inspection devices, regardless of whether two-dimensional systems or CT systems, operate based on the principle of projecting X rays to an image receiver for imaging. An X-ray emitter tube emits X rays which penetrates through a test sample (for example, an electronic circuit board), and a projection is generated on the image receiver according to different absorption quantities of the X rays due to different densities and atomic weights of sample materials, wherein a higher density of the substance indicates a dark shadow. The shadow formed close to the X-ray emitter tube is greater, and the shadow formed far away from the X-ray emitter tube smaller.
A two-dimensional X-ray system simultaneously displays two-dimensional images of all the components on both sides of an electronic circuit board. A three-dimensional CT X-ray system re-constructs image information using a series of two-dimensional images to generate an image of a tangent plane. This technology generates an image of a cross section of a test sample. Another three-dimensional CT X-ray inspection is called X-ray laminography, which reconstructs an image of a cross section by combining image data of a cross section and meanwhile canceling image information of other cross sections. The X-ray laminography system may operate in an online mode or an offline mode. However, during online operation, the speed is low because reconstructing data using a plurality of images takes time. To be specific, a plurality of two-dimensional images and complicated operations are required to reconstruct information, and this process takes several minutes.